FYI @tsteur we have to add the repo alias to the root composer.json for it to be used. In the 2.10.0-rc1 we actually didn't have the "filecache-race-condition-fix" branch code and we were using still doctrine/cache repo. It was fixed in: 41a0e0df6c642b8ddf90f2ea0972418dd89e7e16

Not related to PHP-DI, it's just that piwik-cache uses our fork&branch of doctrine-cache using composer alias. But composer aliases are ignored when they are in dependencies, so the alias works in piwik-cache itself but not when it's included in piwik.

Note: If a package with inline aliases is required, the alias (right of the as) is used as the version constraint. The part left of the as is discarded. As a consequence, if A requires B and B requires monolog/monolog version dev-bugfix as 1.0.x-dev, installing A will make B require 1.0.x-dev, which may exist as a branch alias or an actual 1.0 branch. If it does not, it must be re-inline-aliased in A's composer.json.